R. A. Housley

Radiocarbon evidence for the Lateglacial human recolonisation of Northern Europe

This paper examines, through the use of Accelerator Mass Spectrometry dating, the database of Lateglacial cultures involved in the recolonisation of northern Europe. The aim is not only to determine the timing of that recolonisation, but also to propose a general model of hunter-gatherer colonisation at a sub-continental scale. The question is addressed of how long the period of abandonment of northern Europe during the Wurm/Weichsel glaciation may have lasted, and when it both started and came to an end. A series of questions is asked concerning the processes and mechanics of recolonisation and the sequences for specific areas are examined. AMS radiocarbon dating shows that a two stage process was involved, which has important implications for our analysis of regional settlement patterns and the changing scale of Lateglacial hunting systems. Recolonisation was a dynamic process, integral to, and internally driven by, the social life of Lateglacial hunters. It may have been constrained by environmental and resource factors, which we have emphasised here, but ultimately it was an historical, social process and should be similarily regarded to that of the farmers. By measuring rates of expansion data are provided for use in other studies of hunter-gatherer colonisation.

Eighth Millennium Pottery from a Prehistoric Shell Midden in the Brazilian Amazon

The earliest pottery yet found in the Western Hemisphere has been excavated from a prehistoric shell midden near Santar�m in the lower Amazon, Brazil. Calibrated accelerator radiocarbon dates on charcoal, shell, and pottery and a thermoluminescence date on pottery from the site fall from about 8000 to 7000 years before the present. The early fishing village is part of a long prehistoric trajectory that contradicts theories that resource poverty limited cultural evolution in the tropics.

Volcanic ash layers illuminate the resilience of Neanderthals and early modern humans to natural hazards

Marked changes in human dispersal and development during the Middle to Upper Paleolithic transition have been attributed to massive volcanic eruption and/or severe climatic deterioration. We test this concept using records of volcanic ash layers of the Campanian Ignimbrite eruption dated to ca. 40,000 y ago (40 ka B.P.). The distribution of the Campanian Ignimbrite has been enhanced by the discovery of cryptotephra deposits (volcanic ash layers that are not visible to the naked eye) in archaeological cave sequences. They enable us to synchronize archaeological and paleoclimatic records through the period of transition from Neanderthal to the earliest anatomically modern human populations in Europe. Our results confirm that the combined effects of a major volcanic eruption and severe climatic cooling failed to have lasting impacts on Neanderthals or early modern humans in Europe. We infer that modern humans proved a greater competitive threat to indigenous populations than natural disasters.

Radiocarbon dating of a recent high latitude peat profile: Stor Åmyrân, northern Sweden

The value of both high-precision (HP) and AMS 14C determinations in the fine-resolution dating of recent peat at Stor Åmyrân, near Umeå, northern Sweden has been explored. A detailed chronology of accumu lation, based on 14C, an occurrence of the Askja AD 1875 tephra and 241Am measurements has been derived for the last 700 years. This shows significant changes in the mass balance of the peat profile, with minimum rates of net carbon sequestration overlapping with the period of minimum spring and summer temperature documented by published tree-ring evidence. The paper presents a methodology for calculating empirically past changes in the rate of net carbon sequestration in boreal peatlands and for exploring the effects of climatic variations (and possible future global warming) on these rates.

Results and Methods in the Radiocarbon Dating of Pottery

The main problem with dating pottery by radiocarbon is that many different carbon sources, of different radiocarbon age, may contribute to the potsherd carbon content. Also, the process of firing is liable to destroy information that might help separate possible sources. We describe several pottery dating projects in which we have dated separate fractions (such as humics, lipids and classes of residual carbon). Although in some cases consistency between results is sufficient to accept that this approach can give a credible date, in other cases, no date has been possible, and general conclusions are difficult to make.

Optically stimulated luminescence dating of large storm events in Northern Scotland.

Climate changes over the Holocene have directly impacted on both coastal processes and human use of coastal areas. This paper presents results from the dating of wind blown sand deposits collected from coastal and archaeological sites in Northern Scotland. Archaeological remains are frequently found interspersed with sand deposits and represent distinct periods of occupation of settlement sites within the local landscapes. In some cases storm events sufficiently inundate the sites with sand to result in periodic abandonment. Storm events can also have dramatic results on adjacent rock coastlines, with storm boulder ridges emplaced by large waves, burying sand deposits on cliff-top sites. Work has been undertaken using a quartz SAR protocol to date sand deposition at two archaeological sites in Orkney and a cliff-top site in Shetland. These dates provide chronological information, which help to construct regional chronologies of climatic instability and environmental change and allow the SAR-OSL method to be assessed as an accurate sediment dating tool in this context.

Sea-level change and the archaeology of early Venice

The threatened city of Venice, plauged by rising sea levels and subsiding ground, has been the subject of recent archaeological investigation. Studies of buried archaeological sites yield new evidence on trends in sea-level change for the Lagoon of Venice and provide important insight into how early habitation responded to such change.

Late-Holocene Channel Meander Migration and Mudflat Accumulation Rates, Lagoon of Venice, Italy

Abstract Coring in the Lagoon of Venice mudflats along previously collected high-resolution subbottom seismic-reflection survey profile lines has enabled the collection of interlayered radiocarbon-datable terrestrial plant material. Along present and former meander bends, dipping laminated sandy channel-bank deposits rest in sharp lithostratigraphic and chronologic contrast to the adjacent and overlying mudflat deposits. Horizontal channel migration rates of roughly 10 to 20 meters per century are orders of magnitude faster than the minimum estimates of vertical mudflat silt accumulation, which range from 5 to 25 centimeters per century. Given the nearly 6000-year history since the late-Holocene marine transgression that produced the initial lagoon environments of deposition, it is no surprise that channel meander migration has left a prevalence of channel-bank deposits in the subsurface lithostratigraphy. Furthermore, regional subsidence and rising relative sea level continue to enhance the net accumulation of mudflat and salt marsh deposition on top of the older deposits. Tapered variations of tidal-channel width, depth, and flow velocity, as well as wind-driven waves with associated intensities of turbulence along the meandering paths, lead to recognizable sediment grain size trends and lagoon deposit stratigraphy. Human interventions, such as dredging, spoil disposal, and powerboat wakes, introduce other contrasting processes and depositional features. For complete understanding of the depositional environments in the lagoon, the full set of dynamic processes and depositional consequences often need to be considered. Patterns and processes revealed in this case study probably have broad applicability to other coastal lagoon environments experiencing significant tidal flow and sea-level change.

Cuello; resolving the chronology through direct dating of conserved and low-collagen bone by AMS.

It is well known that 14C dating of fossil bone with seriously depleted protein levels, or bone that has been consolidated with preservatives, can produce erroneous results. In the tropics, warm and moist soil conditions lead to constant reworking of organic matter and add to the danger of bone contamination. Because of this, 14C dating of preservative-impregnated bone from such areas has rarely been successful. We report here a set of AMS dates on both unconsolidated animal bone and polyvinyl acetate/polyvinyl alcohol (PVA/PV-OH) impregnated human burials from the Maya site of Cuello, Belize. The steps needed to purify the samples are described, together with details on the use of qualitative infra-red (IR) spectra as a means of assessing sample purity.

Luminescence dating of aeolian sands from archaeological sites in Northern Britain: a preliminary study ☆

Luminescence dating of aeolian sands from archaeological sites has potential to contribute to regional chronologies for sediment deposition and to provide a greater understanding of climatic influences on early communities. The Northern and Western Isles of Scotland provide important opportunities for sampling archaeologically intercalated sands for these purposes, and to provide constrained samples for method validation. A wide range of modern beaches have been sampled in the Western and Orkney Isles of Scotland to examine regional variations in luminescence sensitivity, residuals and ease of bleaching. These modern sands have negligible residuals for infra-red stimulated luminescence (IRSL), small optically stimulated luminescence (OSL) residuals and significant thermoluminescence residuals. The relationship between these signals and laboratory bleaching results may indicate the initial depositional environment, and hence lead to a means of identifying well-bleached dating samples. Both sensitivities and residuals show regional differences, reflecting local geology. Preliminary ages obtained from aeolian sands associated with archaeological sites at Amble (Northumbria) and Tofts Ness (Sanday, Orkney) using regenerative blue OSL techniques on extracted quartz are broadly consistent with external age controls from the first and third millennium BC.